Force of a 250mm fall

[Khriss]

38 minutes ago, Stubby said:

Having had a couple of Stellas this evening I am going to have to do risk assessment and method statement on how I am going to mitigate any risks  that might arise when I eventually get off this sofa ...

Go steady - tomorrows Sunday , those pews wont polish themselves you know  K

[Khriss]

5 minutes ago, Paddy1000111 said:

@ANK had posted up in the 2 rope consultation thread about the petzl asap no longer being allowed at work and since then has been asking about forces and anchor strengths etc so I just put 2 and 2 together. May be wrong though! 

Wots the reasoning behind it being banned ? Do you know P  ?  K

[Dan Maynard]

Banned is too strong a word, just that his work won't let him use it because it's not designed for tree work.

[Dan Maynard]

The distance you fall is all down to how springy your equipment is, how static your ropes are and how hard your anchor is. I would suggest maybe 50-75mm would be a good distance on 500mm of rope? 

Also how springy/squashy you are, which I think will reduce the forces further. Good upper bound to look at a rigid body.

[Justme]

Do you not use fall factors?

 

So a fall factor of 1 is when the distance you fall is equal to the amount of dynamic rope in the system. Fall factor of 2 you fall double the ropes length.

 

Rock climbers fall many many meters above the anchor but have more rope out to absorb the forces & get a soft catch.

 

Edited February 20, 2021 by Justme

[Justme]

Climbing Fall Forces | Calculate Fall Factor & Impact Force

WWW.ALPINETREK.CO.UK

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What forces are involved in a climbing fall - friction, slack, rope elongation & Co? Can climbing ropes break? ➤ Tool for...

 

[Will C]

Rock ropes are far more stretchy than arb ropes, ours are more static.

Edited February 20, 2021 by Will C
Dam auto correct

[Justme]

Or this one for static rope

 

Fall Factor Calculator

FERFORGE.TRIPOD.COM

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how to fall

 

Edited February 20, 2021 by Justme

[Paddy1000111]

I guess it works it out in the same way as it did in my calculations although it only works if you're above your anchor which we never really are. 

90kg climber, 500mm of rope and 250mm from last anchor is 7.6kn so roughly the same 

[ANK]

@ANK had posted up in the 2 rope consultation thread about the petzl asap no longer being allowed at work and since then has been asking about forces and anchor strengths etc so I just put 2 and 2 together. May be wrong though! 

Exactly that! I’m asking because Petzl mentioned that the ASAP could potentially be used in tree work but that when deployed with a shock absorber it can easily generate 4 to 5kn of force.

So I’m wondering if our anchor points that we select can withstand 4 to 5kn of force? And how much force a 500mm fall generates.

If I can tick all the boxes that Petzl stipulate then I can argue my case to the company I work for.